1. Field of the Invention
This invention relates to a linear slide, more particularly to a linear slide that is durable and that has a high degree of precision.
2. Description of the Related Art
FIG. 1 illustrates a conventional linear slide 1 that includes an elongate guide rail 11, a sliding block 12, and a pair of ball roller chain units 14. The elongate guide rail 11 has a cross-section that is generally rectangular in shape, and has opposite lateral surfaces 112, and a top surface 111 that interconnects the lateral surfaces 112. The sliding block 12 is slidable along the length of the elongate guide rail 11, has a cross-section that is generally U-shaped, and has opposite vertical parts 122, and a horizontal part 121 that interconnects the vertical parts 122. Each of the horizontal and vertical parts 121, 122 of the sliding block 12 confronts a respective one of the top and lateral surfaces 111, 112 of the elongate guide rail 11. Each of the ball roller chain units 14 is disposed between a respective one of the lateral surfaces 112 of the elongate guide rail 11 and a respective one of the vertical parts 122 of the sliding block 12. The construction as such permits the conventional linear slide 1 to achieve a high degree of precision in terms of a linear motion of the sliding block 12 along the elongate guide rail 11.
The conventional linear slide 1 is disadvantageous in that, when a downward force (F1) is applied to the horizontal part 121 of the sliding block 12, the ball roller chain units 14 bear an entire amount of the downward force. This results in a relatively short service life for the ball roller chain units 14.
It has been proposed heretofore to replace the ball roller chain units 14 with cylindrical roller chain units 15, as illustrated in FIG. 2, to solve the above problem. This, however, can cause other problems. That is, the high degree of precision required for the linear motion of the sliding block 12 along the elongate guide rail 11 is undesirably compromised.
In U.S. Pat. No. 6,109,789, there is disclosed a conventional linear slide that includes the elongate slide rail, the sliding block, a pair of the ball roller chains, and a pair of the cylindrical roller chains. Each of the ball roller chains is disposed between a respective one of the lateral surfaces of the elongate guide rail and a respective one of the vertical parts of the sliding block. The cylindrical roller chains are disposed between the top surface of the elongate guide rail and the horizontal part of the sliding block.
Although the ball roller chains provide the high degree of precision required for the linear motion of the sliding block along the elongate guide, and the cylindrical roller chains, which bear a large amount of the downward force, at the same time, facilitate lengthening of the service life of the ball roller chains, when an upward force is applied to the horizontal part of the sliding block, the ball roller chains bear an entire amount of the upward force. This, likewise, results in a relatively short service life for the ball roller chains.